After dodging sharks and jellyfish during her swim from Cuba to Florida, Diana Nyad is now dealing with a different challenge: tough questions from her fellow marathon swimmers about the legitimacy of her achievement.

In the days since Nyad walked out of the water last week at Key West after swimming 110 miles, a stream of questions has come at her.

Could her speed have nearly doubled at one point? Did any of her team members touch her or support her? How could she have gone for hours without food or water?

[Updated at 11:18 a.m. ET] The United States is back as a possible - but unlikely - landing site for a satellite that will be crashing to Earth on Friday or Saturday, NASA says.

The Upper Atmosphere Research Satellite, or UARS, will re-enter the Earth's atmosphere sometime Friday night or early Saturday Eastern Time, according to the space agency. It's too early to predict the time and location of re-entry with precision, but NASA can no longer rule out the United States as a landing spot.

"There is a low probability any debris that survives re-entry will land in the United States, but the possibility cannot be discounted because of this changing rate of descent," NASA said on its website.

NASA previously predicted that the satellite would fall Wednesday afternoon or early evening, Eastern Time, and that the satellite wouldn't be over North America at that time. But "the satellite‚Äôs orientation or configuration apparently has changed, and that is now slowing its descent," NASA's website said Friday.

They know they missed it. Forecasters at the National Hurricane Center in Miami say when it comes to the strength of Hurricane Irene as it approached North Carolina, they know they were off. Way off.

‚ÄúAt least in the guidance we were looking at there was no indication of anything that would cause the storm to weaken. So, we thought we would have a Category 3 at landfall,‚ÄĚ said Bill Read, the director of the Hurricane Center. Irene came in at a Category 1, the weakest. Read said there‚Äôs good reason they were so far off.

The science of forecasting how strong or weak a storm will become is simply not very good. With Irene, forecasters say they weren‚Äôt even as good as their five-year average.

‚ÄúEvery storm comes up with a surprise,‚ÄĚ Read said. ‚ÄúIn this case it was one where it went downhill. Charlie a few years ago is one that went uphill. Neither case did we see that coming, and that‚Äôs my measure of the fact that we have a long way to go.‚ÄĚ

Bill Read, of the National Hurricane Center, talks about the difficulty of predicting hurricanes.

Hurricane forecasters say they want to get it right all the time. But if you are going to be wrong, they say it's better to be wrong in weakening storms like Irene.

‚ÄúI‚Äôd say a bigger worry than one weakening at landfall is the ‚Äô35 hurricane that came through the Keys," Read said. "Charlie if it‚Äôs a little bigger. Audrey in 1957. Get the picture?‚ÄĚ

In all of these cases, the storms rapidly intensified as they neared the coastline. By then, it‚Äôs too late to order massive evacuations.

So, forecasters had the path right, but the impact of landfall changed what the amount of destruction would be in some areas. Wind shear helped knock down velocity, and unexpected dry air sucked some of the power out of the storm.

"It literally knocked the stuffing out of the eye," Myers said. "It never got its mojo back."

New York City hasn't experienced a big hurricane since 1938 and if some of the current models are accurate the impact could be catastrophic.

A simulation done by the National Oceanic and Atmospheric Administration shows what a Category 2 hurricane could do to a tunnel linking Brooklyn and Manhattan.¬† Donald Cresitello with the U.S. Army Corps of Engineers mapped out some worse-case scenarios.

"If a storm were to occur, it could be catastrophic, given the population density in the Northeast," Cresitello said.

National Hurricane Center computer models and comprehensive studies are chilling. If the worst-case scenarios come true, the impact could be devastating.

Water would be pushed into lower Manhattan, steadily rising. Seawater would pour through the Holland and Brooklyn Battery tunnels.

JFK airport would go under an astounding 20 feet of water. The famous Fulton Ferry boat landing in Brooklyn, a popular spot for young couples to take wedding pictures, could also end up under water. Wall Street could find itself in deep water - about 7 feet. The subway system could also be knocked out.

Cady Coleman is like many moms, unfortunately spending Mother‚Äôs Day away from her family.¬† But unlike the¬†others,¬†Coleman¬†is an astronaut on the international space station, orbiting 220 miles above the Earth.

She‚Äôs the only woman on board.¬† Hopefully, the boys up there gave her Sunday off.¬† Usually each crew member gets one day a week to chill.

Coleman may be an astronaut, but first and foremost she is a mom.¬† Cady sent me an e-mail a few days back. I could tell she was just beaming while writing about how her 10-year-old son, Jamey, had struck out three batters in one inning in his Little League game.

She just sent me this message telling me what it has been like up there, the work she is doing and why it is so important, and her feelings on being so far away on this day.¬† So now, in her words:

‚ÄúBeing a mom is special, and distance doesn‚Äôt change the bond we have with those we love.¬† It never goes away, even when you leave the planet for a few months!¬† It seems like just yesterday that Paolo Nespoli, Dmitry Kondratyev and I strapped ourselves into a frozen and creaking Russian Soyuz rocket, and were launched into space from the Baikonur Cosmodrome in¬†Kazakhstan.¬†¬† For the past five months, I‚Äôve made the International Space Station (ISS) my home in low earth orbit, circling our Earth 16 times every single day at 17,500 miles per hour.¬† From 200 miles above the earth, my husband Josh and sons Jamey and Josiah seem both close¬†‚Äď¬†and far.

"I get to talk to my family almost every day via an internet protocol phone, and once a week we get to see each other on a video conference.¬† I still miss lots of important events and occasions, but thanks to Josh, Jamey writes a short journal entry almost every day.¬† Josh sends it to me and I love to hear about life from the perspective of a 10 year old.¬† Jamey is fond of a cartoon where a small boy and a tiger share adventures and get themselves into all sorts of mischief.

"I brought a small stuffed tiger up here with me and I take photos for Jamey so that he can relate to what his Mom does on the space station.¬† From the tiger‚Äôs perspective, there is a lot of great trouble to get into here on the ISS!

"Life in our ‚Äėzero gravity‚Äô world on the ISS is fascinating.¬† We talk about floating around, but really we get to fly from place to place.¬† It is just like Peter Pan, except that we are grownups!¬† This place brings out the child in all of us, and it is a nice reminder to me to treasure the things and the people that touch my heart.

"I love looking out the window at our Earth¬†‚Äď¬†a fragile oasis in a busy universe.¬† When I see the places that I know¬†‚Äď¬†the places where my family lives¬†‚Äď¬†it makes me feel closer to them, although still a bit wistful and lonely when I see those places recede over the horizon.

"It was hard for me to go so far away, but I‚Äôm hoping that I set an example for my child and others to follow their dreams.¬† My family knows that I love the work that I am doing up here, and that I think it is important enough to be gone from home for so long.

"Today as I look down at our beautiful Earth, I think of mothers everywhere and realize that we are all of one family.¬† I am not the only one who is farther from their loved ones than they would wish to be.¬† Today we celebrate those women who are supporting their families, following their dreams and making a difference, and we thank all of them.

"I‚Äôd especially like to thank the women who serve our countries in jobs that keep them from home on holidays like this one.

"Happy Mother‚Äôs Day to my mom, step mom, mother-in-law and to moms everywhere.‚ÄĚ

Diver Bill Burt with¬†Mel Fisher‚Äôs Treasures was looking for a section of the sunken Spanish galleon, Nuestra Senora de Atocha, this week. Instead, he came across¬†a 40- inch gold chain shimmering on the sandy ocean floor¬†about 30 miles from Key West.

The chain, which¬†is believed to have come from the Atocha,¬†contains a gold medallion and a gold cross. ¬†The cross appears to be, according to the salvors, inscribed with Latin letters. ¬†It is estimated to be worth $250,000.

Mel Fisher‚Äôs team found a portion of the Atocha and $450 million worth of artifacts and treasure in 1985. ¬†But the contents of the Atocha‚Äôs sterncastle, a wooden, fort-shaped area at the back of ship, have never been recovered. The Atocha sank during a hurricane in 1622. ¬†A second hurricane is believed to have torn the sterncastle from the Atocha and carried it miles away.

Editor's note: John Zarrella was the CNN network correspondent on site when the 1986 Challenger shuttle disaster occurred. He recalls that day:

When I went to the Kennedy Space Center on January 28, 1986, to cover the launch of the space shuttle Challenger, I was expecting it to be routine, like the launches I had covered in the past. The only thing different this time was the excitement that surrounded the first teacher-turned-astronaut, Christa McAuliffe.

It was brutally cold, and the weather caused the launch to slip several times during the morning. Just before launch, I walked down to the countdown clock, as was tradition among the journalists, and waited for liftoff. I remember that typical winter clear-blue sky as Challenger took off. FULL POST

Three Americans have cast their ballots from the most remote polling station in the solar system - the International Space Station, soaring 220 miles above Earth.

Navy Capt. Scott Kelly, U.S. Army Col. Douglas Wheelock and physicist Shannon Walker used a special secure line to the Johnson Space Center, which relayed the votes to the astronauts' respective home counties.

"It's an honor and a privilege to exercise our right as U.S. citizens to vote from the International Space Station," said Kelly, who voted on Sunday.

Space Shuttle Atlantis sits on the launch pad as it prepares for what may be the shuttle's final flight.

The astronauts were all on board. The hatch was closed.¬† George Diller, voice of launch control, said, "the astronauts appear to be starting their pressure checks."

As I listened to the commentary I could not help but think how all this was coming to an end.¬† In many ways, it's going to be an agonizing end.

This is supposed to be the last flight of the orbiter Atlantis.¬† Maybe.¬† There are only two flights left after this. Maybe.¬† Instead of a clean-cut ending to the shuttle program,¬† it looks as if this will be a long, drawn out and agonizing¬† march to the end.

You hear it's massive - but that word oftentimes is used too loosely. In this case, it is sadly the right choice.

We had just left Houston's Hobby Airport when the captain came on saying if the clouds weren't too thick, we'd be flying right over the oil slick in the Gulf on our way to Fort Lauderdale, Florida.¬† He'd let us know.

Less than an hour later, he's back on the speaker, "If you're sitting on the left side of the plane, that's the mouth of the Mississippi."

We were flying at 39,000 feet, he said.¬† With the clouds only scattered, we'd have a good look at the slick out of both sides of the plane.

From that altitude, I wondered how much I would see - probably not much.

Within minutes, it was below us - the oil stretched out in long, rust-colored streaks, tentacle after tentacle like the arms of a dozen octopus.

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